Apparatus for the manufacture of indented corrugated paper products



c. Q. IVES April 18, 1939.

APPARATUS FOR THE MANUFACTURE OF INDENTED CORRUGATED PAPER PRODUCTS Filed Nov. 9, .1957 2 Sheets-Sheet 2 April 18, 1939.

c IVES v APPARATUS FOR THE MANUFACTURE OF INDENTED CORRUGATED PAPER PRODUCTS 2 Sheets-Sheei 1 Filed Nov. 9, 1957 f ZW/M Km Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR THE MANUFACTURE OF INDENTED CORRUGATED PAPER PROD- UCTS Charles Quincy Ives, Beading, Masa, assignor to Sherman Paper Products Corporation, Newton, Mass, a corporation of Massachusetts Application November 9, 1937, Serial No. 173,629

2 Claims. (01. 154-30) crossing lines intersecting the corrugations at a substantial angle, for instance, an angle of about 45. Such a single-faced :corrugated paper productis disclosed in my United States Reissue Patent No. 20,034, dated July 14, 1936, as being of value for wrapping purposes, since it flexes readily at all angles across the corrugations as well as along lines parallel to the corrugations and can thus be made to assume satisfactorily the external configuration of the body or package being wrapped, especially at corners or edges, with the corrugations affording} essentially the same cushioning or protective effect on the wrapped body or package as when the corrugations are not locally indented.

In producing flexible, single-faced corrugated paper products of the foregoing type, I have observed that it is sometimes difficult to indent permanently tov the desired sharpness or depth the corrugations of certain grades of corrugated paper. This difficulty arises particularly in the case of relatively hard or snappy corrugated papers, such as corrugated kraft paper, glassine paper, parchment paper, etc., whose corrugations are so resilient that they tend to recover or spring backto a pronounced undesirable degree at their locally indented regions after the indenting pressure has been removed therefrom.

The apparatus of the present invention is adapted for the manufacture of a single-faced corrugated paper sheet that is indented locally along lines intersecting the corrugations while the localities being indented are simultaneously treated or wetted with a fiber-softening or plasticizing agent enabling the retention permanently of the indentures in the corrugations substantially as originally created or impressed. It thus becomes possible to produce single-faced corrugated paper products of appropriate flexibility across the corrugations even when the corrugations of the corrugated paper ply are of comparatively high resiliency and'recovery after local indentation in the absence of a fiber-softening or plasticizing agent. While it is possible by the apparatus hereof to treat or wet the corrugated localities being indented in the course of the indenting operation with various fiber-softening or plasticizin'g agents, such as glycerine, oil, etc., yet water or aqueous compositions have been found to be quite satisfactory and least expensive for this purpose. ."that water softens'or plasticizes paper sufilcient- It is evidently the case ly to enable the fibers in the corrugated localities being indented 'to rearrange themselves permanently to the indented or broken-down configuration imparted to the corrugations at the time of their indentation orlocal break-down. Because indentation or local break-down of the corrugations and the fiber rearrangement incident thereto weakens the corrugated paper ply at its indented localities, it is distinctly preferable to use as the softening or plasticizing medium for such localities an aqueous composition containing a suitable bmder that strengthens or bonds together the fibers at the regions of indentation or break-down of the corrugations. Various aqueous binder compositions, including aqueous solutions or suspensions of starch, glue sodium silicate, gums, etc. may serve as fibersoftening agents for'the purposes hereof, but it is preferable to employ aqueous. compositions containing flexible binders, such as, rubber latex, artificial aqueous rubber dispersi0ns, aqueous asphalt emulsions, aqueous emulsions of nitrocellulose, aqueous cellulose xantha'te solutions, or the like. These binders thus set'or dry out in the indented regions of the, corrugations .to strengthen or toughen such regions against tearing or rupture while avoiding undesirable stiffening of such regions.

The indentation of the corrugations of the corrugated paper ply alongclosely spaced lines intersecting the corrugations is readily and continuously effected by providing in the apparatus her of rolls whose peripheries present indenting elements in the form of ribs or knives. The application of the fiber-softening. or plasticizing agent to the corrugations at their localities being indented can be effected economically in the course of the indenting operation by depositing a film of such agent continuously on'the edges of such ribs or knives immediately before they pass into indenting or pressure contact with the corrugated paper ply. Thus, the liquid plasticizing agent may be transferred conveniently in film form by a suitable transfer roll to the edges of the indenting knives or ribs from the periphery of a roll rotating partially submerged in a bath of suchplasticizing agent. If desired, the

plast icizing agent may be dyed or pigmented so that when transferred or deposited in the indentures or recesses of the indented corrugations, colored lines of attractive or ornamental appearance are developed in'the finished flexible corrugated paper product hereof.

dented or flexible corrugated paper product.

Figure 5 shows in greatly enlarged perspective view a fragment of the indented or. flexible corrugated paper product.

Since the single-faced corrugated paper sheet may be produced as customarily by progressively corrugating a continuous paper sheet and then adhesively and progressively securing the corrugated sheet at the crests or apices of its .corrugations .to a continuous flat or plane paper sheet, it is unnecessary to illustrate the machine elements for producing such single-faced corrugated paper sheet. Accordingly, Figure 1- shows the prefabricated single-faced corrugated sheet S consisting of the corrugated paper ply l0 and the flat paper facing ply II as it is being progressively or continuously delivered from the corrugating and facing machine with its facing Ply adhesively bonded to the corrugated ply where the crests l2 of the corrugations make contact with the facing ply. The single-faced corrugated sheet S is preferably subjected to a two-stage indenting treatment, namely, a firststage indenting treatment between a pair of rolls l3 and i4 and a second-stage indentingtreat- 4 'ment between rolls I5 and IS. The upper rolls I3 and I5 of the two pairs of rolls are the indenting rolls and the lower rolls I l and I6 are the base or backing rolls on which the sheet S is supported as the corrugated paper ply is being indented. The periphery of the indenting roll l3 presents multiple spiral ribs or threads I! which, as best appears in Figure 5, are of substantially triangular cross-section and extend as continuous helical elements from one end of the roll to the other. While the ribs Il may occur at various angularities to the corrugations of the corrugated-paper ply, it is preferable that the angularity be substantially 45 so that the indmtures-created in the corrugations of the.

corrugated paper ply will run along lines inters'ecting the'corrugations at substantially 515. The ribs I! may be formed on a steel roll periphery by machining the-roll on a lathe equipped with a cutting tool-carrier whose milling or cutting toolundergoes rotation as well as longitudinal traverse of the roll. The desired angularity'of the-helical ribs or threads I! may thus be determined by the rate of rotation and longitudinal travel of the cutting tool relative to the roll. The number of multiple ribs .or threads l1 thus cut in the roll periphery "may vary, depending upon its diameter and the spacing of indentures to be created in the corrugated paper ply. It is, however, desirable that the successive or multiple spiral ribs I! be spaced apart so that the lines of indenture created thereby in the'corrugated paper ply are spaced about 1%" to from one another. The indenting roll l5 has a ribbed peripheral configuration essentially similar to that of the roll i3, excepting that its mul tiple helical ribs or threads are arranged substantially perpendicularly to the threads of the roll I 3. In passing under the successive indenting rolls, the corrugations of the corrugated pa per ply are thus indented along closely spaced criss-crossing lines l8 intersecting the corrugations at angles of substantially 45.

In order to maintain the indentures in the corrugations of the desired depth, as originally impressed, after the corrugated sheet has emerged from under the indenting rolls l3 and IS, the fiber-softening or plasticizing agent may be progressively deposited on the edges of the ribs l1 immediately before they contact with and indent the corrugations of the corrugated paper ply. To this end, such agent may be transferred in liquid film form to the edges of the ribs I! from a transfer roll l9 makingwiping contact with the periphery of a roll 20 rotating partially submerged in a bath 2| of such agent. By regulatin the speed of rotation of the roll 20 in the bath 2| of such agent, it is possible to control the thickness of the liquid film or amount of agent picked up by the periphery of the roll 20 and thence transferred by the periphery of the transfer roll l9 to the edges of the ribs I1. Each of the rolls l3 and I5 are shown equipped with similar 'instrumentallties for depositing progressively a film of the fiber-softening or 'plasticizing agent to all of the edges of the ribs 11.

As already indicated, the fiber-softening or plasticizing agent may advantageously be an aqueous binder composition, forinstance, rubber latex, which may be dyed or pigmented to any desired color. Indeed, the agent for the roll ll may be of a different color than that for the roll i5 so as to impress or print criss-crossing lines of different colors for pleasing ornamental effect in the indentures created in the corrugations of the corrugated. ,paper ply. 'As appears best in -Figure 5, the softening agent, although applied by the edges ofthe ribs I! essentially only at the bases of the regions of indenture, may difluse or migrate more'or less upwardly over the inclined walls of theindentures. Thei'lbers of the paper are thus softened or plasticized precisely in those regions where the paper corrugations undergo maximum indenture; and such softening or plasticizing action on the. fibers practically inhibits tendency for the indented regions of the paper corrugations to recover or reassume to any significant extent their original corrugated form. The plasticization and permanent rearrangement of the. paper fibers or paper portions constituting.

the regions of indentation of the corrugations is accompanied by some weakening of the paper at such regions of indentation, but this weakening efiect may bemore than oflfsetby the bonding together of the rearranged fibers with therubher or other binder left as a dried residue at such regions, as indicated at 22, from the fiber-softening or plasticizing composition. The finished or indented corrugated paper product is thus without-tendency to tear on the regions "or lines of indentation l8, which regions may, in fact, be

of distinctly greater toughness and tear-resist anceithan the rest of the product.

'I'hewater of the fiber-softening'medium ap plied locally to the regions. of indenture of the corrugation of the corrugated paper ply may be allowed to evaporate naturally-therefrom, although such', evaporation may be hastened by passing the indented corrugated paper sheet S as it comes from under the indenting roll I5 over a hot drier drum 23 pn its way to a rewinding reel 24. Should the medium contain dispersed rubber, asphalt, and/or pigment dyes, or similar agents, the evaporation of the water sets or dries such agents. In some instances, the sheet S may be dried after the indentation and localized w'etting of its corrugated paper ply, as by passage through a hot air chamber, and cut into individual sheets of predetermined size for packaging and sale.

So far as concerns the plane or flat paper facing of the flexible corrugated paper product hereof, it is possible to use in lieu thereof flexible facing fabrics, such as cheesecloth, linen, etc. It is also possible to use in lieu thereof papers of a crinkled or creped nature either alone or reinforced by fabric. Accordingly, in characterizing the indented or flexible corrugated paper product as a single-faced corrugated paper sheet, it is to be understood that the flat facing sheet may be paper or such equivalents of paper as I have just indicated. In respect of the indenting 50 rolls I3 and I5, whose peripheries present multiple helical ribs or threads as the indenting elements, it might be noted that in actual practice the use of fifteen threads per foot in an indenting roll of approximately 6 diameter with a spacing of about A! between the rib apic'es leads to indented or flexibilized single-faced corrugated paper products eminently satisfactory asa wrapping material. It will be appreciated that the peripheries of both indenting rolls are similarly so configured, excepting that the threads or ribs in one roll extend practically perpendicularly to the threads or ribs in the other roll and that both indenting rolls as well as their base rolls I4 and it are positively driven or rotated at a speed a coordinated preferably exactly with the speed at which the single-faced corrugated paper is being delivered thereto.

I claim: 1. In a machine for locally indenting the cor- 40 rugations oi the corrugated paper ply of a singlefaced corrugated paper sheet and thereby rendering said sheet readily flexible across its corrugations,,a pair of coacting rolls through whose nip said sheet may be passed, said pair of rolls including an indenting roll whose periphery presents multiple closely spaced helical ribs by which the corrugations of said corrugated paper ply may be indented along lines intersecting said corrugations at an angle, and a second pair of coacting rolls through whose nip said'sheet may be passed from said first pair of rolls, said second pair of rolls including an indenting roll whose periphery also presents closely spaced helical ribs by which the corrugations of said corrugated paper ply may be intended along lines intersecting said corrugations but criss-crossing the lines of indentation created in the corrugations by the ribs of said first-named indenting roll.

2. In a machine for locally indenting the cor-- rugations of the corrugated paper ply of a singlefaced corrugated paper sheet and thereby rendering said sheet readily flexible across its corrugations, a pair of coacting rolls through whose ni'p said sheet may be passed, said pair of rolls including an indenting roll whose periphery presents multiple closely spaced helical ribs by which the corrugations of said corrugated paper ply may be indented along lines intersecting said corrugations at an angle, a second pair oi coacting rolls through whose nip said sheet may be passed from said first pair of rolls, said second pair of rolls including an indenting roll whose periphery also presents closely spaced helical ribs by which the corrugations of said corrugated paper ply may be indented along lines intersecting said corrugations but criss-cromng the lines of indentation created in the corrugations by the ribs of said first-named indenting roll, and means for progressively depositing a fllm of liquid on the edges of the ribs of each said indenting rolls before they make contact with said corrugated paper ply..

CHARLES QUINCY IVES. 

